The invention relates to an occupant protection device for a driver""s side of a motor vehicle.
DE 195 01 859 A1 discloses a protection arrangement for a motor vehicle, in which a support element which is detached from a splashboard is rigidly connected to elements of the vehicle body whose position is virtually unchanged even in the event of an accident. The steering spindle of the motor vehicle is likewise connected to the support element, via a bearing. The steering spindle is furthermore mounted on a steering framework, the mounting being designed to be flexible in a specifically predetermined way. As a result, in the event of a crash, the steering spindle is pivoted downwards, so that an airbag installed in the steering wheel is brought into an improved position with respect to an occupant.
The steering spindle is designed to be telescoping and is designed with an integrated force limiter. Furthermore, in the event of a crash a foot pedal is moved away from the occupant by means of an actuating rod.
The disadvantage of this arrangement is the fact that in the event of a crash the force which is necessary for displacement of the steering spindle and which is introduced by the occupant is not adjusted to the severity of the accident.
The invention is based on the object of configuring the deformation performance of a steering system in the event of a vehicle crash in such a manner that said performance automatically sets itself to an occupant""s mass and vehicle deceleration.
According to the invention, in the case of an occupant protection device for a driver""s side of a motor vehicle, in which a steering spindle is guided in a steering-column tube, and a steering wheel is preferably provided with an airbag. The steering spindle is arranged such that it can move in the direction of its longitudinal axis, and said steering spindle is assigned at least one energy-absorbing element.
The advantage of the displaceable steering spindle resides in the fact that the entire steering gear, also including additional subassemblies secured on it, is moved away from the occupant in the event of a crash. As this happens, more or less energy is absorbed depending on the intensity of the impact on the occupant.
It is expedient for an energy-absorbing element to be arranged to adapt automatically to the mass and relative speed of the occupant colliding with the steering wheel or the airbag. This makes it possible to further reduce the risk of injury to the occupant.
This arrangement according to the invention can be realized in a number of embodiments.
Thus, in a first embodiment, provision is made for the steering-column tube to be guided displaceably on at least one holding part which is connected to a vehicle crossmember, which is very largely non-displaceable in the event of a crash. Provision is also made for the energy-absorbing element to be arranged between the steering-column tube and the holding part, the steering spindle being non-displaceable in the steering-column tube. The arrangement of a holding part, which is very largely non-displaceable in the direction of the occupant in the event of a crash, ensures that the steering-column tube, which is mounted displaceably in said holding part, and therefore the steering spindle is displaced away from the occupant. Even if the splashboard, which separates the passenger compartment from the engine compartment, is displaced by the impact in the direction of the occupant the tube and steering spindle are displaced away from the occupant.
It is expedient for the holding part, which is connected to the vehicle crossmember, to have at least one slot in which a guide pin, which is connected to the steering-column tube, engages. It is also expedient for a hydraulic arrangement with a piston and a cylinder to be provided as the energy-absorbing element, the piston being connected to the steering-column tube or to the holding part, and the cylinder being connected to the other part in each case. The holding part preferably has two slots which essentially extend in the direction of the longitudinal axis of the steering-column tube and which are each assigned a guide pin. Each guide pin is secured on a connecting part which is connected to the steering-column tube.
In a further refinement, provision is made for the steering-column tube to have, at its end which faces the occupant, at least one support for a switch unit. This support additionally serves as an element which impedes the deformation of the steering wheel in the event of a crash and therefore prevents the airbag from being deployed in the direction of the vehicle roof instead of in the direction of the occupant.
In a further refinement, a pedal-assembly auxiliary support is provided which is secured pivotably on the holding part at one end, is furthermore secured pivotably on the steering-column tube, and on whose other end is secured to at least one of the clutch, brake and gas pedals. The arrangement of the pedals in this manner achieves the effect that said pedals are pivoted away from the occupant in the event of a crash. The pedal-assembly auxiliary support is expediently connected to the steering-column tube via a clamping device. Releasing this clamping device enables the pedal assembly to be adjusted to the occupant before thejourney is begun. Once the clamping arrangement is fixed in position, the pedal-assembly auxiliary support is connected fixedly to the steering-column tube, so that in this embodiment too, the described advantageous action occurs in the event of a crash.
In a second embodiment, the steering-column tube is connected fixedly to the very largely non-displaceable vehicle crossmember, and the steering spindle can be displaced in the steering-column tube, in the direction of its longitudinal axis. In the case of this embodiment, the steering spindle can therefore be displaced directly.
In a further refinement of this embodiment, a guide bush (or bushing) for the steering spindle is provided in the steering-column tube. The guide bush is rotatable, but is axially non-displaceable, in the steering-column tube. The steering spindle can only be displaced axially in the guide bush. The steering spindle is expediently provided with a serration which is assigned a corresponding serration in the guide bush.
In this embodiment, the steering spindle and the guide bush expediently form a piston-cylinder arrangement, in which the cylinder space is divided by the piston into two chambers which can be connected to each other via at least one valve. Preferably, a plurality of valves which are connected in parallel are provided. A number of valves which differs as a function of the occupant""s mass and relative speed of the occupant is brought into a working position. This is brought about by means of sensors which are known per se and by means of an associated control system.
Instead of valves which are connected in parallel, at least one valve having a variable cross section may also be provided.